Ages, was the necessity of keeping close to the shore. It is true they might guide themselves by the sun during the day, and by the pole-star at night, but if once the sky was overcast, they would become entirely at a loss for their bearings. Hence the discovery of the polar tendency of the magnetic needle was a necessary prelude to any extended voyages away from land. This appears to have been known to the Chinese from quite ancient times, and utilised on their junks as early as the eleventh century. The Arabs, who voyaged to Ceylon and Java, appear to have learnt its use from the Chinese, and it is probably from them that the mariners of Barcelona first introduced its use into Europe. The first mention of it is given in a treatise on Natural History by Alexander Neckam, foster-brother of Richard, Cœur de Lion. Another reference, in a satirical poem of the troubadour, Guyot of Provence (1190), states that mariners can steer to the north star without seeing it, by following the direction of a needle floating in a straw in a basin of water, after it had been touched by a magnet. But little use, however, seems to have been made of this, for Brunetto Latini, Dante's tutor, when on a visit to Roger Bacon in 1255, states that the friar had shown him the magnet and its properties, but adds that, however useful the discovery, "no master mariner would dare to use it, lest he should be thought to be a magician." Indeed, in the form in which it was first used it would be of little practical utility, and it was not till the method was found of balancing it on a pivot and fixing it on a card, as at present used, that it became a necessary part of a sailor's outfit. This practical improvement is attributed to one Fiavio
